1. Field of the Invention
The present invention relates to a canvas stretching and framing device upon which canvas or other sheet material may be stretched. Particularly, this invention relates to a unique canvas stretcher and framing device having fixed, square comers and easily adjustable straight sections.
2. Brief Description of Prior Art
As is well-known in the art, oil paintings on canvas are conventionally mounted on wooden frames which are sometimes referred to as canvas stretchers. The canvas stretcher as known in the prior art is assembled with interlocking comers which form a miter joint between the straight sections of the canvas stretcher. The canvas is affixed to one edge of the canvas stretcher using staples or nails, draped over the opposite side of the frame, manually stretched taught, and stapled or nailed to the frame. During this process, a certain amount of force is applied to the canvas stretcher which can result in the miter comers shifting out of a square orientation.
These traditional miter comers also have the disadvantage of complicating any desired changes in the size of the frame. In order to change the size of the frame, the artist must be familiar with certain sophisticated woodworking techniques and have the necessary equipment to create a miter joint.
In the past, a number of adjustable frames have been disclosed. Three examples of such frames are U.S. Pat. Nos. 4,050,498, 4,179,830 and 4,144,660, all of which have been improved upon by the instant invention. The adjustable frames disclosed by the patents noted above are very complex from a mechanical standpoint and thus are difficult and expensive to manufacture. For example, U.S. Pat. No. 4,179,830 discloses corner segments which are made up of no less than five separate parts and include moving parts. U.S. Pat. No. 4,144,660 similarly has corner segments involving multiple elements including moving parts. U.S. Pat. No. 4,050,498 discloses a frame device having corner sections comprised of not less than four discrete parts including a spring-like "adjusting element."
Known adjustable frames also require that the straight sections of the frame have 45.degree. mitered ends. This limits the ease with which these straight sections can be cut down and reduced in length. Creating a mitered corner requires a certain advanced knowledge of woodworking techniques and equipment. Also, commercially available canvas stretchers ordinarily have 45.degree. mitered comers with one or more projecting legs, and respectively one or more recesses which join with the adjacent frame member. This complicated joinery further limits the ease with which the size of the frame may be altered or resized.
A further problem with presently known and currently available canvas stretching devices is that they are not designed in such a way that they may effectively and simply adjust for any expansion or contraction of the canvas due to changes in environmental conditions. Commercially available canvas stretching devices attempt to alleviate this problem by requiring the insertion of spacers into each of the mitered comers in a way that expands the joints. Construction of mitered comers in a way that allows for adjustment in this fashion is complex. Both construction and use of this kind of stretching mechanism requires several working steps.
Canvas stretched upon a canvas stretcher, moreover, exerts inward force on the perimeter of the canvas stretcher which can result in distortions of the canvas stretcher. The constant inward force exerted by the canvas can cause the perimeter of the canvas stretcher to warp and bow toward the center of the canvas. In order to avoid this, braces are often placed across the back of the canvas stretcher. These braces are ordinarily tacked onto the back of the stretcher resulting in a painting which cannot be hung flush against a wall as a result of the protruding braces.
A further problem facing commercially available canvas stretchers is the deterioration of a painting that occurs with age. It has been found that canvas paintings deteriorate at the point of contact of the canvas with the frame. It is believed that this damage is due to the reaction of the paint on the canvas with the wood material of the canvas stretcher itself caused by the resins and acids in the wood.